Chondroma of Soft Tissue

Background

Soft-tissue chondromas are benign cartilage-forming tumors that usually arise from tenosynovial sheaths or the soft tissue adjacent to tendons in the hands and feet of adults. They consist entirely of mature hyaline cartilage. When these tumors undergo secondary changes such as dystrophic calcification, enchondral ossification, hemorrhagic or myxoid degeneration, infiltration by granulomatous inflammation, or CPPD deposition, these tumors may be difficult to distinguish from other cartilaginous tumors including a malignant chondrosarcoma. The pathologist must coordinate the light microscopic findings with the radiologic appearance to arrive at the correct diagnosis.

PATHOGENESIS CHARACTERIZATION

Involvement of chromosomes 6 and 11 in a soft tissue chondroma.

Dal Cin P, Qi H, Sciot R, et al.
Cancer Genet Cytogenet 1997;93:177–8.

HISTOLOGICAL TYPES CHARACTERIZATION

General
Majority are composed entirely of lobules of mature hyaline cartilage

In some variants the cartilage matrix becomes extensively mineralized, which is often associated with necrosis of chondrocytes, causing the tumor to resemble tumoral calcinosis

Hyaline cartilage may also undergo enchondral ossification, mimicking an osteogenic neoplasm or a reactive lesion

May exhibit variable degrees of cytologic atypia, including enlarged cells, moderate pleomorphism, hyperchromasia, and binucleation, making it difficult to exclude a malignancy

May demonstrate myxoid degeneration that can cause confusion with extraskeletal myxoid chondrosarcoma

Approximately 10% of soft-tissue chondromas contain epithelioid histiocytes and osteoclast-like multinucleated giant cells that are usually concentrated at the edges of the chondroid matrix or within septae that delineate cartilaginous lobules and may resemble giant cell-rich lesions such as localized nodular tenosynovitis or crystal deposition disease

VARIANTS

Chondroblastoma-Like Chondroma of Soft Tissue An Underrecognized Variant and Its Differential Diagnosis

Justin M. Cates, etal.

Am J Surg Pathol 2001;25:661-666 Abstract quote

Soft-tissue chondromas are usually composed entirely of mature hyaline cartilage. Infrequently, however, they may exhibit morphologic features that result in diagnostic difficulty.

The authors report a series of eight hypercellular soft-tissue chondromas composed of enlarged chondrocytes within a variable amount of chondroid matrix that often demonstrated delicate calcifications and contained numerous osteoclast-like multinucleated giant cells. This histologic appearance closely resembles that of chondroblastoma of bone. However, its extraosseous location, dense cellularity, and poorly formed cartilage can cause confusion with more aggressive chondroid neoplasms of soft tissue.

The clinicopathologic features of these chondroblastoma-like chondromas are discussed, emphasizing the characteristics that facilitate their accurate identification.

DIFFERENTIAL DIAGNOSIS KEY DIFFERENTIATING FEATURES

Other cartilaginous tumors of soft tissue Tenosynovial giant cell tumor (nodular tenosynovitis), calcifying aponeurotic fibroma, EMC, metastatic chondroblastoma, and conventional skeletal chondrosarcoma

Cartilaginous differentiation in peritoneal tissues: a report of two cases and a review of the literature.

Fadare O, Bifulco C, Carter D, Parkash V.

Departments of Pathology, Yale University School of Medicine (OF, DC, VP), New Haven, Connecticut and Istituto Nazionale Tumori (CB), Milano, Italy.
Mod Pathol 2002 Jul;15(7):777-80 Abstract quote
Two cases of cartilaginous differentiation of the peritoneum not associated with an intraabdominal malignancy are described.

This is the first detailed report of cartilaginous metaplasia of the peritoneum. The patients were female, ages 53 (Patient 1) and 77 years (Patient 2). Prior medical histories were significant for a culdotomy (to drain pelvic abscesses associated with pelvic inflammatory disease) in Patient 1 and for an open abdominal surgery in Patient 2. The peritoneal lesions were incidental findings in both cases. In Patient 1, surgery was performed for a septated ovarian cyst; the other patient underwent surgery to relieve obstructive bowel symptoms. In Patient 1, multiple firm, white lesions ranging from 2.0 to 7.0 mm were present on the serosal surfaces and the mesenteries of the small and large bowel. In Patient 2, a single firm, white lesion measuring 2 cm in maximum dimension was removed from the mesentery of the ileum.

Microscopically, the lesions consisted of small nodules of mature hyaline cartilage surrounded by nondescript fibrous tissue and covered by mesothelium. There was no foreign body giant cell reaction, inflammation, or other reactive changes in the surrounding adipose tissue.

These may represent metaplastic lesions of the secondary mullerian system, or a unique peritoneal response to previous surgical manipulation. Alternatively, these may represent benign neoplastic lesions (chondroma) of the submesothelium.

Cancer 1978;41:1414–24.

Commonly Used Terms

Bone Tumors

Soft Tissue Tumors

Last Updated 8/19/2002

HISTOLOGICAL TYPES	CHARACTERIZATION
General	Majority are composed entirely of lobules of mature hyaline cartilage In some variants the cartilage matrix becomes extensively mineralized, which is often associated with necrosis of chondrocytes, causing the tumor to resemble tumoral calcinosis Hyaline cartilage may also undergo enchondral ossification, mimicking an osteogenic neoplasm or a reactive lesion May exhibit variable degrees of cytologic atypia, including enlarged cells, moderate pleomorphism, hyperchromasia, and binucleation, making it difficult to exclude a malignancy May demonstrate myxoid degeneration that can cause confusion with extraskeletal myxoid chondrosarcoma Approximately 10% of soft-tissue chondromas contain epithelioid histiocytes and osteoclast-like multinucleated giant cells that are usually concentrated at the edges of the chondroid matrix or within septae that delineate cartilaginous lobules and may resemble giant cell-rich lesions such as localized nodular tenosynovitis or crystal deposition disease
VARIANTS
Chondroblastoma-Like Chondroma of Soft Tissue An Underrecognized Variant and Its Differential Diagnosis Justin M. Cates, etal.	Am J Surg Pathol 2001;25:661-666 Abstract quote Soft-tissue chondromas are usually composed entirely of mature hyaline cartilage. Infrequently, however, they may exhibit morphologic features that result in diagnostic difficulty. The authors report a series of eight hypercellular soft-tissue chondromas composed of enlarged chondrocytes within a variable amount of chondroid matrix that often demonstrated delicate calcifications and contained numerous osteoclast-like multinucleated giant cells. This histologic appearance closely resembles that of chondroblastoma of bone. However, its extraosseous location, dense cellularity, and poorly formed cartilage can cause confusion with more aggressive chondroid neoplasms of soft tissue. The clinicopathologic features of these chondroblastoma-like chondromas are discussed, emphasizing the characteristics that facilitate their accurate identification.